Impeller for a centrifugal pump and centrifugal pump

ABSTRACT

An impeller for a centrifugal pump has at least one vane which has a lower side concavely curved in at least one part region and which has at least one kink line in at least one part region. The kink line extends at least substantially along a main direction of extent of the at least one vane. The vane is open in a V shape along the kink line in at least one part region in the direction of a surface normal of the lower side.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National stage application of International Application No. PCT/EP2014/057885, filed Apr. 17, 2014, which claims priority to EP Application No. 13164139.1, filed on Apr. 17, 2013, the contents of each of which is hereby incorporation herein by reference.

BACKGROUND

1. Field of Invention

The invention relates to an impeller for a centrifugal pump having an impeller.

2. Background Information

Some conventional impellers for centrifugal pumps have at least one vane which has an upper side which has at least one kink line in at least one part region. The vanes are in this respect open in a V shape along the kink line in the direction of a surface normal of an upper side, i.e. an opening of the vanes faces in a direction of rotation in which the impeller is rotated in an operation to generate a pump effect.

SUMMARY

It is in particular the underlying object of the invention to provide an impeller by which a characteristic of a centrifugal pump can be improved. The object is satisfied by an impeller in accordance with the invention described herein.

The invention starts from an impeller for a centrifugal pump having at least one vane which has a lower side curved concavely in at least one part region and which has at least one kink line in at least one part region, which kink line extends at least substantially alone a main direction of extent of the lower side.

It is proposed that the vane is at least open in a V shape along the kink line in at least one part region in the direction of a surface normal of the lower side. Since the vane of the impeller has a V shape which is open exactly conversely in comparison with the prior art, a flow behavior can in particular be improved within the pump wheel, whereby in particular a characteristic of a centrifugal pump can be improved. A “vane” should in this respect in particular be understood as a component of the impeller which forms a wall of a pump space and which has the radially outwardly facing upper side which generates a pump effect in an operation. A “pump chamber” should in this respect in particular understood as a volume bounded by the impeller which connects a radially inwardly disposed suction region to a radially outwardly disposed pressure region. The pump chamber can in this respect generally be divided into a plurality of part chambers which are disposed axially behind one another and which all connect the same suction region to the same pressure region. It is, however, generally also conceivable that the impeller has a plurality of different pump chambers which are disposed axially behind one another and which each connect different suction regions to a single pressure region. A “lower side” should in this respect in particular be understood as a surface which is formed by the vane and whose surface normal has a component which is directed radially inwardly with respect to an axis of rotation of the impeller. A “kink line” should in this respect in particular be understood as a line defined by a spatially tightly bounded curvature of the vane. A radius of curvature is preferably substantially larger in the region of the kink line than a radius of curvature in adjacent regions. The radius of curvature in the region of the kink line advantageously amount to at most some millimeters. Depending on the rounded portions in the region of the kink line, the radius of curvature can, however, also be in the range of tenths of a millimeter or in the range of hundredths of a millimeter. The reference indications “axial”, “radial” and “in the peripheral direction” should here and in the following relate to the axis of rotation of the impeller, provided nothing explicitly different is stated. “Open in a V shape” should in this respect in particular be understood such that the lower side forms an open V, i.e. such that the surface has two part surfaces which are arranged at both sides of the kink line and which face one another, with the V preferably opening radially inwardly starting from the kink line.

The at least one vane preferably has an opening angle spanned by the kink line at the lower side which is smaller than 180 degrees in at least one part region. The V-shaped opening can thereby be particularly advantageously realized. An opening angle should in this respect in particular be understood as a clearance angle which the two mutually facing part surfaces include with one another.

It is further proposed that the opening angle has a bisectrix in at least one part region which lies at least substantially in a plane which is oriented perpendicular to an axis of rotation. A symmetrical design of the vane can thereby be achieved, whereby an improved flow behavior can in particular be achieved in the pressure region. A “bisectrix of the opening angle” should in this respect in particular be understood as a line which intersects the kink line and which divides the opening angle into two part angles of equal amounts. “At least substantially” should in this respect in particular be understood such that an angle which is included by the plane perpendicular to the axis of rotation and by the bisectrix is smaller than 5 degrees. The angle between the plane perpendicular to the axis of rotation and the bisectrix is preferably smaller than 3 degrees and particularly preferably smaller than 1 degree.

It is furthermore advantageous if the bisectrix and the kink line span a plane which is oriented perpendicular to an axis of rotation. The vane can thereby be formed symmetrically with respect to a plane perpendicular to the axis of rotation, whereby a particularly advantageous flow behavior can in particular be achieved in the pressure region.

The lower side of the vane preferably has at least two part surfaces which are each arranged on one side of the kink line and which include an acute angle with a plane perpendicular to an axis of rotation. The V-shaped design of the lower side can thereby be achieved particularly easily. An acute angle should in this respect be understood as an angle smaller than 90 degrees, with the angle preferably being determined in a direction parallel to the axis of rotation.

It is moreover proposed that the angles between the plane perpendicular to the axis of rotation and the part surfaces are each smaller than 80 degrees. An advantageous opening angle of the lower side can thereby be achieved. The angles are preferably smaller than 75 degrees. The angles are particularly advantageously smaller than 70 degrees.

In a particularly advantageous further development, the part surfaces have an at least substantially planar design in the axial direction. A “planar design in the axial direction” should in this respect in particular be understood such that the lower side of the vane can be described by a straight line along at least one longitudinal sectional plane in the region of the part surfaces. The opening angle is preferably defined by a relative alignment of the two part surfaces relative to one another and can be determined in the longitudinal sectional plane. A “longitudinal sectional plane” should in this respect be understood as a section along a plane which has the axis of rotation.

It is further proposed that the impeller has two impeller disks which are laterally adjacent to the at least one vane and with which the part surfaces of the lower side of the vane include an obtuse angle in at least one part region. The pressure chambers bounded by the vanes in the radial direction can thereby also simply be bounded in the axial direction, with the V-shaped configuration of the lower side in such a design extending over a total axial width of the vane in the at least one part region. An “obtuse angle” should be understood as an angle larger than 90 degrees, with the angle preferably being determined in a direction parallel to the axis of rotation. The angles between the impeller disks and the part surfaces can thus in particular be determined at a longitudinal sectional plane. An “impeller disk” should in this respect in particular be understood as a disk which is arranged perpendicular to the axis of rotation and which bounds the pressure chambers of the impeller in the axial direction. The vanes and the chambers can generally be designed at least partly in one piece or in multiple pieces.

The at least one vane preferably has a symmetrical cross-section in at least one longitudinal sectional plane. A particularly advantageous configuration can thereby be achieved, in particular with respect to the characteristic of the centrifugal pump and/or a construction design. A “symmetrical cross-section” should in this respect in particular be understood as a mirror-symmetrical design with respect to a plane perpendicular to the axis of rotation.

It is moreover proposed that the at least one vane has an at least substantially unchanging thickness in at least one sectional plane. The impeller can thereby be further improved. An “unchanging thickness” should in this respect in particular be understood such that the thickness of the vane, i.e. its dimension perpendicular to the lower side, is at least substantially constant along a line in the sectional plane.

It is furthermore advantageous if the opening angle amounts to at least 60 degrees and/or to at most 160 degrees. The lower side can thereby be advantageously configured. The opening angle preferably amounts to at least 80 degrees and/or to at most 130 degrees. The opening angle particularly advantageously amounts to at least 100 degrees and/or to at most 120 degrees.

In addition, it is proposed as a further development that the impeller has a center wall which is in particular arranged in the region of the kink line. The pump chambers of the impeller can thereby be in a technical flow aspect divided into part volumes axially disposed behind one another, whereby a particularly advantageous flow behavior can be achieved. A “center wall” should in this respect in particular be understood as a wall for dividing pump chambers into two part volumes connected in parallel from a technical flow aspect. A center wall should in particular not be understood as a radially throughgoing impeller disk which forms a multistage or two-pass impeller. A “multistage impeller” should in this respect in particular be understood as an impeller which has a plurality of suction regions connected behind one another in a technical flow aspect. A “two-pass impeller” in particular be understood as an impeller which has two suction regions connected in parallel in a technical flow aspect and which has pump chambers adjoining each of the suction regions, with the suction regions being connected via the pump chamber to a single common pressure region in a technical flow aspect.

The impeller can generally have a single-pass design having a single suction region and having a single pressure region connected to the one suction region in a technical flow aspect. Alternatively, however, it is also conceivable that the impeller has a two-pass design having two suction regions disposed axially opposite one another, having an impeller disk separating the two suction regions and having a common pressure region connected to the two suction regions in a technical flow aspect. An impeller with a two-pass design is in this respect fed with fluid from both sides, whereas an impeller having a single-pass design is only fed with fluid from one side.

In addition, a centrifugal pump having an impeller in accordance with the invention is proposed.

Further advantages result from the following description of the Figures. Two embodiments of the invention are shown in the Figures. The Figures, the description of the Figures and the claims contain a number of features in combination. The skilled person will also expediently consider the features individually and combine them to further sensible combinations.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of this original disclosure:

FIG. 1 is a representation of the prior art;

FIG. 2 is a perspective representation of an impeller in accordance with the present invention of a centrifugal pump;

FIG. 3 is a longitudinal section through the impeller along a longitudinal sectional plane;

FIG. 4 is an enlarged representation of a part region of FIG. 3; and

FIG. 5 is an embodiment of an impeller having a center wall.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 shows an impeller 110 for a centrifugal pump such as is known in the prior art. The impeller 110 generates a pump effect. To generate the pump effect, the impeller 110 comprises a plurality of vanes 111 which have a concavely curved lower side 112 and a convexly curved upper side 126. The vanes 111 each have a kink line 113 which extends along a main direction of extent of the vanes 111. The vanes 111 are open in a V shape along the kink line 113 in the direction of a surface normal of the upper side 126, i.e. an opening of the vanes 111 faces in a direction of rotation in which the impeller 110 is rotated in an operation for generating the pump effect.

FIG. 2 shows a centrifugal pump in a two-pass design and FIGS. 3 and 4 show in partly schematic form a centrifugal pump in a single-pass design having an impeller 10 a in accordance with the invention which generates a pump effect. The centrifugal pump comprises a pump housing, not shown in any more detail, in which the impeller 10 a is rotatably supported, and a drive flange 21 a, which is rotationally fixedly connected to the impeller 10 a and which connects the impeller 10 a to a drive machine not shown in any more detail. The impeller 10 a, which is rotatably supported about an axis of rotation 17 a, has a radially inwardly disposed suction region 28 a and a radially outwardly disposed pressure region 29 a.

To generate the pump effect, the impeller 10 a comprises a plurality of vanes 11 a. The vanes 11 a each have an upper side 26 a which is remote from the axis of rotation 17 a and a lower side 12 a which faces the axis of rotation 17 a. The vanes 11 a, which are each formed in an analog manner, are uniformly distributed over a periphery of the impeller 10 a. The vanes 11 a are arranged spirally with respect to the axis of rotation 17 a. The upper sides 26 a of the vanes 11 a are substantially concavely curved. The lower sides 12 a of the vanes 11 a are substantially convexly curved.

In addition, the impeller 10 a comprises two impeller disks 22 a, 23 a, which are adjacent to the vanes 11 a at both sides. The impeller disks 22 a, 23 a are arranged substantially perpendicular to the axis of rotation 17 a. Together with the vanes 11 a, the impeller disks 22 a, 23 a form a plurality of pump chambers 30 a which effect a pressure difference between the suction region 28 a and the pressure region 29 a in an operation. The pump chambers 30 a are bounded by the impeller disks 22 a, 23 a in the axial direction. The pump chambers 30 a are bounded radially inwardly by the upper side 26 a of a respective one of the vanes 11 a. The pump chambers 30 a are bounded radially outwardly by the lower side 12 a of the respectively following vane 11 a. The vanes 11 a and the impeller disks 22 a, 23 a are formed in one piece in the embodiment shown. A multipart design is, however, generally also conceivable.

In an operation, the upper sides 26 a of the vanes 11 a act as pressure surfaces. The pump effect is substantially due to an extent of the upper sides 26 a of the vanes 11 a. If the impeller 10 a rotates about the axis of rotation 17 a, the upper sides 26 a form pressure surfaces which, in conjunction with a centrifugal force induced by a rotary movement of the impeller 10 a, convey a medium to be pumped, in particular liquids, radially outwardly.

The vanes 11 a each have a kink line 13 a which substantially extends along a peripheral direction. The kink line 13 a extends along a main direction of extent of the vanes 11 a and thus along main directions of extent of the lower side 12 a and of the upper side 26 a. The vanes 11 a respectively form a kink along the kink line 13 a at the upper side 26 a and at the lower side 12 a and said kink extends axially centrally over the upper side 26 a and the lower side 12 a at least in an outer part region of the corresponding vane 11 a. The kink line 13 a lies at the upper side 26 a and at the lower side 12 a in a plane 16 a which is oriented perpendicular to the axis of rotation 17 a.

The kink line 13 a along which the upper side 26 a and the lower side 12 are respectively kinked extends in the embodiment shown only in the outer part regions of the vanes 11 a in the peripheral direction. In inner part regions, in particular in the suction region 28 a, the kink line 13 a is guided in the direction of a margin of the vanes 11 a, whereby the kink line 13 a extends obliquely to the peripheral direction. The kink line 13 a is in this respect in particular guided up to the margin of the vane 11 a in the suction region 28 a, whereby the vanes 11 a in the embodiment shown are inwardly kink-free and only have the kink outwardly.

The impeller 10 a can be adapted to different demands made on the centrifugal pump by varying an extent of the kink line 13 a. In particular an axial position which the kink line 13 a has at different radii can differ from the embodiment shown. For example, the kink line 13 a can also be led radially outwardly to a margin of the vanes 11 a, for example to provide the vanes 11 a with a kink which extends along the main direction of extent of the vanes 11 a from the one margin diagonally over the corresponding vanes 11 a to the other margin. In this respect, middle part regions which lie between the outer part region of the vanes 11 a and an inner part region can generally also be formed kink-free while the inner and outer part regions have a kink.

The vanes 11 a are each open in a V shape along their kink line 13 a in the direction of a surface normal of the lower side 12 a. The vanes 11 a have an opening angle 14 a at the lower side 12 a along the respective kink line 13 a, said opening angle being smaller than 180° at least in the part regions in which the corresponding vane 11 a is kinked. The opening angle 14 a which defines an opening of the vane 11 a is directed radially inwardly. In a longitudinal sectional plane, i.e. a sectional plane in which the axis of rotation 17 a lies, the lower side 12 a has a V-shaped structure (cf. FIG. 4). A point at the lower side 12 a of the corresponding vane 11 a which lies on the kink line 13 a has a larger spacing from the axis of rotation 17 a than all further points on the lower side 12 a of the corresponding vane 11 a which lie in the same longitudinal sectional plane. The kink line 13 a thus forms a radially outer point of the lower side 12 a in the corresponding longitudinal sectional plane in all longitudinal sectional planes at least in the outwardly disposed part regions.

The opening angle 14 a has a bisectrix 15 a which is directed parallel to the peripheral direction. The bisectrix 15 a thus extends in a plane 16 a which is oriented perpendicular to the axis of rotation 17 a. The kink line 13 a extends in the same plane 16 a. The bisectrix 15 a and the kink line 13 a thus span the plane 16 a extending perpendicular to the axis of rotation 17 a. The bisectrix 15 a lies along the total kink line 13 a in the plane 16 a which is oriented parallel to the axis of rotation 17 a.

The lower side 12 a of the vane 11 a has part surfaces 18 a, 19 a at both sides of the kink line 13 a which include an acute angle 20 a, 21 a with the plane 16 a perpendicular to the axis of rotation 17 a which is spanned by the bisectrix 15 a and the kink line 13 a. The two part surfaces 18 a, 19 a are inclined toward one another. The part surfaces 18 a, 19 a each include an angle 20 a, 21 a of approximately 60-65 degrees with the plane 16 a which extends perpendicular to the axis of rotation 17 a. The opening angle 14 thus amounts to approximately 120-130 degrees. The angles 20 a, 21 a between the part surfaces 18 a, 19 a and the plane 16 a perpendicular to the axis of rotation 17 a can generally be between 5 degrees and 70 degrees. It is in this respect in particular also conceivable that the opening angle 14 a varies along the kink line 13 a, in particular when the lower side 12 a is kink-free in a part region. The opening angle 14 a can merge successively from a specific value, for example 120 degrees, along the main direction of extent of the vanes 11 a into a kink-free state in such an embodiment.

The part surfaces 18 a, 19 a have a planar design in the axial direction. The part surfaces 18 a, 19 a are only curved in the peripheral direction. In a section along the longitudinal sectional planes, the part surfaces 18 a, 19 a have a planar extent (cf. FIG. 3). In a section in the plane 16 a perpendicular to the axis of rotation 17 a, the part surfaces 18 a, 19 a are curved. The part surfaces 18 a, 19 a at the lower side 12 a of the vane 11 a include a respective obtuse angle 20 a, 21 a with the impeller disks 22 a, 23 a which are laterally adjacent to the vane 11 a. The angles 24 a, 25 a which the part surfaces 18 a, 19 a at the lower side 12 a respectively include with the impeller disks 22 a, 23 a each amount to approximately 120-130 degrees. The impeller disks 22 a, 23 a each include an angle 31 a, 32 a of approximately 60 degrees with the upper side 26 a of the vane 11 a. The angles 24 a, 25 a at the lower side 12 a and the angles 31 a, 32 a at the upper side 26 a are each formed complementary to one another.

The vanes 11 a have a substantially unchanging thickness at least in the outer part regions, i.e. in a corresponding longitudinal sectional plane, the radial thickness of the vanes 11 a is substantially constant. The upper side 26 a thereby has a shape which corresponds to the V-shaped design of the lower side 12 a. At the lower side 12 a, the outwardly facing surface of the vane 11 a has the V-shaped design which is radially inwardly open. At the upper side 26 a, a material of the vane 11 forms the same shape, with the material having the inwardly open V-shaped design.

The vane 11 a has a symmetrical cross-section in the longitudinal sectional plane. The plane 16 a perpendicular to the axis of rotation 17 a which is spanned by the bisectrix 15 a and the kink line 13 a forms a plane of symmetry. The vane 11 a is formed with mirror symmetry in the outer part region with respect to the plane 16 a. The vane 11 a is formed asymmetrically in the inner part region, in particular in the suction region 28 a.

A further embodiment of the invention of a centrifugal pump in a double-pass design is shown in FIG. 5. The following descriptions are substantially restricted to the differences between the embodiments, with reference being able to be made to the description of the embodiment of FIGS. 2 to 4 with respect to components, features and functions which remain the same. To distinguish the embodiments, the letter a in the reference numerals of the embodiment in FIGS. 2 to 4 is replaced with the letter b in the reference numerals of the embodiment of FIG. 5. Reference can generally also be made to the drawings and/or the description of the embodiment of FIGS. 2 to 4 with respect to components of the same name, in particular with respect to components with the same reference numerals.

FIG. 5 shows a detail of an impeller 10 b for a centrifugal pump in a double-pass design, said impeller having a plurality of vanes 11 b, wherein in the present cross-sectional view only one vane is visible. The vanes 11 b each have a concavely curved lower side 12 b and a convexly curved upper side 26 b. In addition, the vane 11 b has a kink line 13 b which extends along a main direction of extent of the vane 11 b. The lower side 12 b has a surface normal which is oriented perpendicular to a surface of the vane 11 b at every point of the kink line 13 b. The vane 11 b is open in V shape in the direction of the surface normal of the lower side 12 b along the kink line 13 b. In addition, the impeller 10 b comprises two impeller disks 22 b, 23 b which adjoin the vanes 11 b at both sides and which, together with the vanes 11 b, each span pump chambers 30 b for conveying a fluid to be pumped.

Unlike the preceding embodiment, the impeller 10 b comprises a center wall 33 b which divides the respective pump chambers 30 b into two part volumes 34 b, 35 b arranged axially behind one another. The center wall 33 b is arranged in the region of the kink line 13 b. The center wall 33 b extends in a portion substantially parallel parallel to the impeller disks 22 b, 23 b. The center wall 33 b enables advantageously that liquid respectively aspirated through the suction region 28 b does not apply directly to each other in the intake for improved pumping action. The center wall 33 b fluidically divides the pumping chamber 30 b into two part volumes 34 b, 35 b arranged axially behind one another.

The impeller 10 b has a radially inwardly disposed suction region 28 b which is connected in a technical flow aspect to the part volumes 34 b, 35 b disposed axially behind one another. In addition, the impeller 10 b has a radially outwardly disposed pressure region 29 b which is likewise connected in a technical flow aspect to the part volumes 34 b, 35 b disposed axially behind one another. Each of the part volumes 34 b, 34 b thus connects the inwardly disposed suction region 28 b to the outwardly disposed pressure region 29 b.

The center wall 33 b which divides the pump chambers 30 b into the part volumes 34 b, 35 b arranged axially behind one another is formed in the manner of an elevation at the so called hub of the centrifugal pump. The suction region 28 b is arranged within the center wall 33 b. The pressure region 29 b is arranged outside the center wall 33 b. The center wall 33 b is arranged radially inside in respect of the vane 11 b.

The impeller 10 b is arranged at a drive shaft 27 for driving the impeller 10 b. 

1. An impeller for a centrifugal pump, comprising at least one vane having a lower side concavely curved in at least one part region and having at least one kink line in the at least one part region, the kink line extending at least substantially along a main direction of an extent of the at least one vane, the vane being open in a V shape along the kink line in at least one part region in the direction of a surface normal of the lower side.
 2. An impeller in accordance with claim 1, wherein the at least one vane has at the lower side an opening angle which is spanned by the kink line and which is less than 180 degrees in the at least one part region.
 3. An impeller in accordance with claim 2, wherein the opening angle has in the at least one part region a bisectrix lying at least substantially in a plane oriented perpendicular to an axis of rotation.
 4. An impeller in accordance with claim 3, wherein the bisectrix and the kink line span the plane oriented perpendicular to the axis of rotation.
 5. An impeller in accordance with claim 1, wherein the lower side of the vane has at least two part surfaces arranged on oppositely disposed sides of the kink line and which include a respective acute angle at the kink line with a plane perpendicular to an axis of rotation.
 6. An impeller in accordance with claim 5, wherein the angles between the plane perpendicular to the axis of rotation and the part surfaces are each less than 80 degrees.
 7. An impeller in accordance with claim 5, wherein the part surfaces have an at least a substantially planar configuration in the axial direction.
 8. An impeller at least in accordance with claim 5, further comprising two impeller disks laterally adjacent to the at least one and with which the part surfaces of the lower side of the vane include an obtuse angle in at least one part region.
 9. An impeller in accordance with claim 1, wherein the at least one vane has a symmetrical cross-section in at least one longitudinal sectional plane.
 10. An impeller in accordance with claim 1, wherein the at least one vane has a substantially constant thickness in at least one sectional plane.
 11. An impeller in accordance with claim 1, wherein the opening angle is at least 60 degrees and at most 160 degrees.
 12. An impeller in accordance with claim 1, further comprising a center wall arranged in a region of the kink line.
 13. An impeller in accordance with claim 1, wherein the impeller is configured to operate in a one-pass design.
 14. An impeller in accordance with claim 1, wherein the impeller is configured to operate in a two-pass design.
 15. A centrifugal pump comprising an impeller in accordance with claim
 1. 